1. Field of the Invention
The present invention relates to an image forming apparatus including a fusing roller that heats a developed image transferred to a recording medium and fuses the same on the recording medium.
2. Description of the Related Art
In an image forming apparatus of this type, reduction of the time required from reception of a print command until the start of an actual printing process is demanded. In addition, improvement of technology to adjust the temperatures of a fusing roller and its peripheral components is also demanded because waving or curling of a recording medium may result when there are temperature fluctuations of the fusing roller or a significant temperature difference between the fusing roller and the peripheral components (for example, a nip roller) during fusing. When the fusing roller is rotated longer than necessary, increased power consumption and noise may result. Therefore, rotation of the fusing roller should be restrained as much as possible.
In order to facilitate quick heat-up of the fusing roller, countermeasures such as reduction of the thickness (reduction of heat capacity) of a metal tube which constitutes the fusing roller, and arrangement of a heater at a position deviated from the axis of rotation of the fusing roller, are now in progress. However, such countermeasures increase the possibility of temperature fluctuations in the fusing roller and temperature differences between the fusing roller and the peripheral components (for example, abrupt increase of the temperature of the fusing roller in comparison with the peripheral components when heated).
In order to restrain temperature fluctuations and temperature differences from the periphery of the fusing roller, it is useful to heat the fusing roller while it is being rotated. However, increasing rotation of the fusing roller may increase noise and power consumption.